Btrfs: open_ctree: Fix possible memory leak

After reading one of chunk or tree root tree's root node from disk, if the
root node does not have EXTENT_BUFFER_UPTODATE flag set, we fail to release
the memory used by the root node. Fix this.
Signed-off-by: Chandan Rajendra <chandan@linux.vnet.ibm.com>

fs/btrfs/disk-io.c

@@ -2842,6 +2842,8 @@ int open_ctree(struct super_block *sb,
 	    !extent_buffer_uptodate(chunk_root->node)) {
 		printk(KERN_ERR "BTRFS: failed to read chunk root on %s\n",
 		       sb->s_id);
+		if (!IS_ERR(chunk_root->node))
+			free_extent_buffer(chunk_root->node);
 		chunk_root->node = NULL;
 		goto fail_tree_roots;
 	}
@@ -2880,6 +2882,8 @@ int open_ctree(struct super_block *sb,
 	    !extent_buffer_uptodate(tree_root->node)) {
 		printk(KERN_WARNING "BTRFS: failed to read tree root on %s\n",
 		       sb->s_id);
+		if (!IS_ERR(tree_root->node))
+			free_extent_buffer(tree_root->node);
 		tree_root->node = NULL;
 		goto recovery_tree_root;
 	}